Please visit the accompanying website: Life on Nu Phoenicis IV, the planet Furaha.
This blog is about speculative biology. Recurrent themes are biomechanics, the works of other world builders, and, of course, the planet Furaha.

Monday, 2 January 2017

The Book is over half done and is changing as it develops. I started by repainting existing oil paintings digitally, and by now most paintings with a pleasing design have been done. At first the paintings were merely cleaned up and details were added, but in the latest cases not a single pixel from the original painting survived: they were completely recreated from start. More importantly, the content changed: writing more elaborate texts forced many story elements and biological principles to be firmly defined for the first time. The painting 'arrival at Furaha' is a good example of this process (first post here, last one here): painting an internal spaceship scene forced me to turn my previously rather vague ideas how they might work and in-world design aesthetics into written concepts and painted shapes that will guide things coming later.

The next big step will be finally defining hexapod legs: I will have to decide once and for all whether each of the three pairs of legs will start with zigzag pattern or with a zagzig pattern as well. It is the middle pair that causes headaches: its design should not simply mimic that of either the first or the third pair, so how do I make it work? My thoughts on that subject are slowly coalescing.

But meanwhile another thought came up. So far, the animals in the paintings are fairly big and conspicuous; but how about the 'small fry', all those little creatures that together make up much more of the animal biomass than big animals do? Shouldn't I give them some attention? But what of their shapes? Must they all have truly alien shapes, or should they simply look like they were taken from a textbook of Earth invertebrates? Currently, I think the latter probably applies, based on two considerations. The first is the enormous variety of invertebrate shapes on Earth; it is hard to come up with an original design when evolution produced many oddities that would be dismissed as impossible if they were presented as fictional animals. The second consideration is that some principles will apply universally; streamlining must be a universal solution for moving through a fluid at any speed.

The challenge, of course, is to push their design boundaries a bit. They may not always be possible: 'worms' are probably universal. I mean small boneless elongated burrowing animals with a round or flattened cross section. So The Book shall contain at least one spread on 'wurms', and I doubt that I can come up with designs that do not already exist on Earth. A second group to merit attention are arthropod analogues: insects, spiders and the like. I already designed some of those: spidrids and tetropters. But the concept of a small bilateral exoskeletal segmented animal seems so good that it is hard to avoid. I will name the Furahan reprentatives of this design the name 'wadudu'; this is one of the remnant Swahili words left by the spacefarers of the good ship 'Ngonjera'.

Click to enlarge; from http://fox.rwu.edu/jellies/

Earth's oceans are full of jellyfish for the last 500 million years. They are radial bell-shaped organisms without complex nervous systems that move in a simple cycle: the bell contracts, water is pumped downwards and by reaction the animal moves upwards. Then the bell relaxes , becomes broader and lets in water again. This has always seemed a bit odd to me: when the bell relaxes, it flattens but also broadens, which must hinder its upward movement. Also, water has to flow upwards into the bell from below, which must because an equal but opposite reaction pulling the animal down a bit. That was my unconsidered opinion, but recent studies showed that jellyfish swimming is much more sophisticated that I thought. Some swim as I described, by jetting water downwards. Those tend to be bullet-0shaped. The flatter ones drive down a toroidal vortex of rotating water, and that actually pushes water back up underneath the bell, pushing the jellyfish up when the bell is relaxed. Here is a very nice website explaining these matters.

And the video above shows the toroidal vortices that provide propulsion even in the relaxed phase. The paper to which the video belongs was published in PNAS and is freely available.

I wondered whether there was room for creativity here. What if some water can flow downwards right through the jellyfish while it is moving passively in the relaxation phase? Making a hole in the bell will of course impair its propulsive upwards force when the bell contracts, so the hole should be open during the relaxed phase to prevent the animal being sucked down, but closed when it contracts? Valves should do the trick, shaped perhaps like those in the mammalian heart. The ones in the aorta are a useful example: they open when the ventricle pushes blood out, and close to prevent blood flowing back into the relaxed ventricle from the aorta. I decided to play with that idea a bit, and give Furahan jellyfish analogues a twist.

Click to enlarge; copyright Gert van Dijk

Here is such an animal in a rough sketch. The first image shows that there are three valves. Instead of one central bunch of tentacles, as in Earth jellyfish, there are three outlined here. I may make the body less perfectly circular to reflect this triune design.

Click to enlarge; copyright Gert van Dijk

This cutaway shows a section just off centre of the animal, a bit near the camera. The cut goes through the two nearest valves and as you can see they are closed. This is what their position would be during the propulsion phase, when the bell contracts so pressure is high underneath the bell.

Click to enlarge; copyright Gert van Dijk

And here is an open phase, with the valves apart from one another. I should have drawn the rest of the bell in a more relaxed shape, but thought this would be enough to convey the idea.

So there we are: Furahan jellyfish analogues. I do not wish to simply call them 'jellyfish', so they needed a name that would in the Furahan story setting. In Furahan lore, settlers came mostly from a Western European background with a smattering of people from other parts of the world (the down-to-Earth reason for that is that I am only comfortable with a few Germanic and Romance languages). I looked up the word for jellyfish in various languages (here is a site to check some all at once for yourselves). Many languages use variants of Medusa (the Greek monster woman whose hair takes the shape of snakes and whose regard turns you to stone). I like the Brazilian name 'agua-viva', or living water; very poetic. But I will go with the German and Dutch variants of 'Qualle' and 'kwal', words that evoke a soft flabby and unpleasant nature. I considered an anglicised version in the form of 'quall'. To be certain I checked, and found that 'quall' already has a meaning as yet completely unknown to me. Hm. I had better avoid that connotation. So, 'kwal' it will be, unless someone comes up with a better suggestion. Actually, the 'a' in the Gemran and Dutch versions sounds like the 'a' in 'father' or in British
'bath', but for Furahan purposes a pronunciation like an 'o' is the likelier one.